I recently moved my old components into a new tower for my mother in law. I formatted her HD, installed Win 8, everything went perfectly well. She was using the computer for I'd say two hours or so when all of a sudden she saw a message that Windows was shutting down. Once this happened, she tried to turn the PC back on but no luck. I turned it on, it came on for about 3 seconds, not even long enough to post, all 4 phase LEDs lit up. No beeps. I tried a different PSU, same thing. Here's what I do know: The fan on the aftermarket CPU heatsink wasn't spinning. I actually plugged it in to another fan connector to get it going. So she was using the Q6600@ stock speeds for an hour or two with a Xigmatech heatsink. Not sure if the CPU would be permanently damaged from that? I tried a different PSU and had the same result. I removed each stick of ram individually and that did not help. Removed the GPU and that didn't help. The only thing I haven't done is take everything out and reassemble the PC.

Anyways, I don't have another LGA775 motherboard hanging out around here so I thought I'd ask you guys what you think it may be. I did some Google searching and the majority of results included Gigabyte motherboards...Which this is . And most of those boards were now out of commission.

Maybe your fan went bad. I know there's an option in the BIOS to shut down the computer if it fails, so maybe try a new fan. If your mobo was to truly fryed, there wouldn't have been a "Shutting Down Windows" screen--it would have just flip off. It is difficult to fry a modern processor. I'm not saying it can't be done, but it's just hard to do. Are there any lights on the mobo when you plug it in?

Well, it stopped turning on altogether so I couldn't check another fan in the CPU fan connector. I removed everything, reconnected it all, turned on for a few seconds, all 4 phase LEDs lit up again, it *looked* like the CPU fan spun (I was caught off guard by it starting so frantically turned my head to the cpu fan and by then the PC shut off). I tried turning it on again, and now nothing happens. Just a quick, milisecond green phase led light flashes. I can't turn the PC on with the power switch by the way. It only comes on ever so briefly when I turn the PSU to on. Pushing the case power button does nothing. (This is with both power supplies.)

If the motherboard has no on-board GPU you will need one in and try another one then try clearing the CMOS connect only the board , GPU, RAM then remove the heatsink and check the CPU socket and CPU for burn marks and then call it dead if nothing works.

Whenever I am in a situation like you the OP (and it does happen a lot, same symptoms).

My checklist:

1- Check with a new/other PSU + check every connection also from the PSU to the Motherboard, make sure it's not some power connector that isn't properly connected (Yes it happens, sometimes we forget about the basics )!

2- CPU check, while a dead CPU wouldn't shutdown the system at start, it would just give most of the times no bleeps (no POST) at start and a black screen, remove it and try to start the system without it! (Yes it won't properly start but if the system stays say 10s on you now know the CPU might also be dead or also causing problems)

3- At this point if you're looking just for the system to at least be on, remove (the connections to the board) of everything, disks, DVD's, any usb connectors, Firewire, etc.. Just have power to the board, and the the power and led's buttons of the case!

4- If it still doesn't work, sure make a reset of CMOS, etc.. But if the problem still exists you have a dead board, don't spend money on parts to try, just replace the board!

PS: Oh and yes the CPU fan spins for a second and stop's, yep I've seen before

Removed the Xigmatech heatsink, put the stock one on and...**** this is embarrassing to admit...I noticed uhh...The standoffs were not attached to the case >_>. Installed those, reseated everything, got a blue screen or two so re-installed Windows and all is well in the world!

Removed the Xigmatech heatsink, put the stock one on and...**** this is embarrassing to admit...I noticed uhh...The standoffs were not attached to the case >_>. Installed those, reseated everything, got a blue screen or two so re-installed Windows and all is well in the world!